FIG. 4(a) is a plan view showing an IC package having external lead terminals which are bent toward one of the plane surfaces of the package (hereinafter referred to as an A-type IC package). FIGS. 4(b) to 4(d) are a side elevational view, a front elevational view, and a sectional view, respectively, of the A-type IC package. Here, a small outline package (SOP) is employed. As shown in FIG. 4(d), an IC chip 7 disposed on a die pad 10 is electrically connected with external lead terminals 2 by bonding wires 11. The die pad 10, the IC chip 7, parts of the external lead terminals 2 and the bonding wires 11 are encapsulated in a molded plastic to produce the A-type IC package 1a.
FIG. 2 is a plan view showing a prior part semiconductor device in which a pair of A-type IC packages are mounted on one side of a package substrate. In FIG. 2, the A-type packages 1a are mounted on the package substrate 5. Soldering portions 3 of the external lead terminals 2 are connected to the package substrate 5 by solder, and thus the A-type packages 1a are fixed onto the package substrate 5. The A-type packages 1a are connected with each other by wires 9 and through holes 8. The external lead terminals 2 have pin numbers crc .about.crc , respectively.
Description is given of a method for mounting the A-type IC package Ia on the package substrate 5. FIG. 3 is an enlarged sectional view of a lead connection of the A-type IC package. First, solder 4 is previously applied to a mount pad 6 of each electrode portion on the surface of the package substrate 5. Then the package 1a is mounted on the package substrate 5 by soldering the portion 3 of the external lead terminal 2 to the mount pad 6 with the solder 4 and electrically and mechanically connected to the pad 6.
In order to obtain a construction in which two A-type packages 1a are mounted on the substrate 5 and the external lead terminals 2 of the packages having the same numbers of pins are mutually connected with each other as shown in FIG. 2, it is necessary to provide wires 9 in complicated arrangements and also to provide through holes 8 penetrating the package substrate 5.
As described above, in this prior art semiconductor device, a pair of A-type packages are mounted on one surface of the package substrate and the external lead terminals of the packages having the same numbers of pins are connected with each other as shown in FIG. 2. Then, wires 9 inevitably intersect each other and wiring arrangements are provided. Further through holes must be provided penetrating through the package substrate 5.